Component cards or printed circuit board assemblies for mounting and interconnecting electronic components are well-known. Various types of connectors for making physical and electrical interconnection with component cards or printed circuit board assemblies are also well-known. Component cards or printed circuit board assemblies are often interconnected through associated connectors in panel-type assemblies. Connector arrangements account for the insertion and removal of component cards or printed circuit board assemblies.
The low insertion force provides the name Zero Insertion Force (ZIF) connectors. Advantages of ease of insertion and removal of the printed circuit board assembly, minimization of contact wear, and maximization of the number of connector contact for this type of connector have been recognized and described in the prior art.
One example of a low insertion force connector used for making electrical connection between printed circuit board assemblies and external circuitry is disclosed in U.S. Pat. No. 4,540,228 to Steele. It describes an improved linear cam actuating mechanism in the low insertion force connector.
Another example of a zero insertion force (ZIF) connector for electrically connecting I/O pads of a printed circuit board and a set of printed conductors is disclosed in U.S. Pat. No. 4,542,950 to Gillett et al. This patent describes cams actuated to engage contacting of parts.
The disclosure in U.S. Pat. No. 4,636,019 to Gillett et al discloses a connector mechanism for connecting portions of the structures. The disclosed connector mechanism is an effective ZIF connector.
One zero insertion force card seating and locking mechanism disclosed in IBM Technical Disclosure Bulletin Vol. 31, No. 2, pp. 138, 139, dated July 1988, discloses a spring-biased sensor pin which senses the position of an insertable printed circuit (PC) card in a ZIF connector and, if the card is improperly positioned, it prevents the actuation of the ZIF connector. A blunt-nosed spring-biased sensor pin is contained in an opening in the ZIF connector housing body and retained in the openings by a concentric apertured plug housing. A spring biases the sensor pin so that the sensor pin protrudes into the card channel or slot in the connector housing body with just enough force to maintain the sensor pin in position. The connector actuator cam is shown in its open or deactuated position with a through hole or opening in line with or registered with the sensor pin. This opening is configured to have clearance around the sensor pin, permitting free movement of sensor pin against the force provided by the spring. The chamfered or wedge-like part of the entering edge of a PC card or board may be in contact with the card, but not exerting force, on the sensor pin. Once the card enters the ZIF connector's body, the sensor pin is now displaced and protrudes into the hole or opening in the connector actuator cam in its open or deactuated position opening, thereby obstructing the actuating cam. As a result, ZIF actuation is prevented until the card is either withdrawn or is completely inserted in channel or slot. When the card is in its home position, the spring forces the sensor pin to the right where it is in interference with the chamfered or wedge-like part of the exiting edge of the PC card. The sensor pin is now clear of the opening in the actuating cam, so the cam can be operated as shown to move closing contacts of the ZIF connector against the contacts on the PC card. With the cam in such a position, it prevents movement of the sensor pin and, thus, the card is held in place in the mechanism.
It should be particularly noted that the edges of the card which come in contact with the sensor pin are chamfered to enhance the action of the card moving the plunger of the sensor pin. The opposite edge of the card is tapered to provide a polarization function. Therefore this zero insertion force card seating and locking mechanism may be an improved mechanism for cards. The card may be inserted in the channel or slot with its planars reversed. As a result, the sharp flat corner of edge of card engages the parallel side of the sensor pin, thus preventing the card from being fully inserted in the connector slot. Therefore this ZIF card seating and locking mechanism may be an improved mechanism for cards.
A low-cost ZIF connector system disclosed in IBM Technical Disclosure Bulletin, Vol. 31, No. 4, pp. 55, 56, dated September 1988, describes a method of connecting together PC boards to PC cards and flexible PC cables using a low-cost, ZIF connector. The basic connector can be operated by various methods to apply a contact force after insertion. Options described are mechanical cam-operated or sliding-wedge operated using a solenoid or memory alloy compression springs. In all methods, a contact wiping action occurs when the connector is closed. The flexible cable is continuous; only one component is needed to connect several connectors together. The design allows the flexible cable to be omitted where expedient. The connector will then accept a single card. In this case, the design will provide output pins on the connector. The connector block includes parallel multi-pin contacts accepting a PC card. An unbroken flexible printed circuit tape cable with conducting bands on both sides is sandwiched between the slot formed by the left and right hand clamps of the connecting block passing under a retaining roller. Contacts are arranged on clamps to mate with the conductors on the flexible cable. Coincident conductors on the opposite side of the flexible cable mate with contacts on the inserted PC card.
When the card is fully inserted, the sides of the connector block are clamped inwards by raising the end plate assembly by rotating the cam manually. The clamps are brought together by the action of the pins on the end of the clamps sliding in the diagonal slots. The end plates are raised and lowered by the slotted disc and pin arrangement.
The result of the clamps being pivoted at their base is to cause the flexible cable edge to have a downward component of motion as the clamps close. This drags the clamp surface across the back of the flexible cable which also pulls across the card which has been inserted. The connector may be opened and closed to release or grip the card edge connector. The flexible surface is forced to wipe the card edge connector, this being an important requirement for making a reliable contact. The amount of wiping action is governed by the relative friction coefficients between the clamp and the back of cable and the front of cable and the card.
An alternative to the manual cam arrangement of raising and lowering the end plate array may be used. A sliding wedge actuator is operated by a solenoid or a memory compression spring to overcome a permanent bias tension spring. Heat energy from a resistance is applied to the memory spring only during the period of replugging.
A cam-actuated Zero Insertion Force connector disclosed in IBM Technical Disclosure Bulletin, Vol. 30, No. 5, pp. 289, 290, dated October 1987, discloses a pair of cams judiciously positioned at each end of a side-entry edge-card connector actuated by the card, which in turn actuates the spring contacts of the connector. The improved arrangement includes a pair of cams, the cams being located at the opposite end of a ZIF connector, the details of which are not shown for the sake of clarity. The cams pivot about points and have the configurations shown. A movable element is a driving piece or cam which is coupled to the ZIF springs to operate the springs between their contacting and non-contacting positions. The operation taking place during the insertion of a card in the direction from left to right. At this time the card moves over the flat portion of cam and drive member. When the right side of the card comes in contact with the cam, it causes the cam to rotate clockwise, with the result being that the driving piece moves to the left. In turn, the cam is forced to rotate in a clockwise direction, so that the card is locked in place. Concurrently, the motion of driving piece to the left closes the connector's springs, establishing contact between them and the card contact tabs.
When a card is extracted, the card is pulled to the left, and the left edge of the card engages the cam and rotates it counterclockwise, whereupon the driving piece is moved to the right, and it in turn causes the cam to rotate counter-clockwise, to thereby return to its initial position.
Previous ZIF connectors have also employed handles to actuate them. Since the present arrangement eliminates the requirement for handles, it provides several advantages. Space is no longer required for handle travel, thereby reducing the overall size of the package. Secondly, the space previously occupied by the ZIF handle in the package is now available for air flow which enhances the cooling of the package. Assembly time is reduced by the elimination of the time required to actuate the handles. Card cocking problems occurring because only one handle at a time can be actuated are eliminated. With the present arrangement, top and bottom ZIF connectors would be actuated simultaneously, eliminating card cocking and thus insuring good electrical contact between the ZIF springs and the card tabs.
It is an object of this invention to provide a zero insertion force connector having a horizontally slidable cam system that moves a retention lobe into contact with a positioner that is connected to and positions a component card with contact tabs on it. The positioner includes a lobe opening that provides physical positioning of the component card tabs in relation to the connector contacts positioned in the zero insertion force connector when the retention lobe is mated.
In accordance with these and other objects which will be apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.